Serb protesters in northern Kosovo blocked roads for a second day on Sunday following an exchange of fire with police.
Trucks and other heavy-duty vehicles blocked several main roads leading to two border crossings with Serbia.
Longstanding tensions between authorities and Kosovo's Serb minority have been rising in recent weeks.
The latest protests were triggered by the arrest of a former Serb police officer on Saturday.
Prime Minister Albin Kurti described the protesters as "criminal gangs" and asked the Nato-led peacekeeping Kosovo Force (KFOR) to remove the barricades.
The EU called for peace to be restored, saying a stun grenade hit one of its armoured vehicles patrolling northern Kosovo on Saturday evening.
Kosovo police said they came under fire in different locations close to a lake bordering Serbia late on Saturday, with officers returning fire in self-defence.
It comes after Kosovo deployed police to majority-Serb areas - which do not recognise the Kosovo government in the capital Pristina - at the end of last week. This heightened tensions further, after they were already raised for months over a row about vehicle license plates.